Crankcase lubricating oil and additive therefor



United States Patent CRANKCASE LUBRICATING OIL AND ADDITIVE THEREFOR John D. Bartleson, Franklin, Mich., assignor to The Standard Oil Company, Cleveland, Ohio, a corporation of Ohio No Drawing. Application September 30, 1953, Serial No. 383,366

Claims. (Cl. 252-375) The present invention relates to a crankcase lubricating oil for internal combustion engines which contains a minor proportion of an additive that is efiective in reducing the accumulation of undesirable deposits in the combustion chamber of an engine as well as suppressing octane requirement increase normally resulting from operation of such engines, as well as to the additive per se.

It is well known that the operation of an internal combustion engine, initially clean, results in a formation of progressively greater amounts of deposits on the surfaces of the combustion zone, i. e., on the cylinder head, piston top and the intake and exhaust valves, until the amount of deposits reaches a level beyond which no appreciable further increase in amount of deposits are apparent upon continued operation. This increase in deposits is manifested most clearly to the operator of the engine, particularly an automobile engine, by the fact that the presence of the deposits in the engine requires a fuel having a higher octane rating in order not to knock than is required by a new or clean engine. This means, in other words, that the octane value of a fuel required by an engine containing deposits in the combustion zone in order not to knock (referred to hereinafter as octane requirement) is higher than the octane requirement of a clean engine. For example, a clean engine which requires a gasoline having an octane rating of 60 in order not to knock is said to have an octane requirement of 60. Ifthe same engine, when dirty, i. e., with deposits in the combustion chamber, requires a gasoline having an octane rating of 75 in order not to knock, such an engine is said to have an octane requirement of 75 or an octane requirement increase of 15. When upon continued use the octane requirement of the engine increases no further,'it is believed that the engine has then reached deposit equilibrium. This is believed to be due to the fact that after a certain amount of deposits have been formed inthe combustion zone, additional amounts of deposits either fail to adhere to the deposits already formed or the rate of formation of additional deposits becomes about equal to the rate at which the deposits flake off and are removed through the exhaust of the engine.

The present invention is based on the surprising discovery that combinations of silver naphthenate with copper or nickel naphthenate, when present in minor amounts in a crankcase lubricating oil, are effective in suppressing octane requirement increase and have synergistic effects in inhibiting the formation of combustion chamber deposits as well as in inhibiting the deterioration of the lubricating oil. The additive of the present invention, therefore, essentially comprises a mixture of silver naphthenate with copper or nickel naphthenate and the lubricating oil of the invention is essentially one containing a minor proportion of such an additive.

. additive.

The relative proportions, in the additive, of the silver naphthenate on the one hand and the copper or nickel naphthenate on the other hand may vary considerably. Relative proportions by weight ranging from about 1:3 to about 3:1 being most desirable and approximately equal proportions, i. e., about 1:1 being preferred. Extremely small concentrations of the additive in the lubricating oil exert some desirable efiects in suppressing octane requirement increase and inhibiting the formation of combustion chamber deposits, larger concentrations up to about 2% by weight producing these effects in an increasing'degree. Ordinarily, it is desirable, in order to obtain such effects to an appreciable degree to have the additive present in a concentration of at least about 0.2% by weight. Due to economic considerations and the fact that concentrations of additive greater than about 2% by weight do not produce the desired effects in an appreciably greater degree than concentrations below 2%, it is generally not considered practicable that the lubricating oil contain more than about 2% by weight of the Generally, therefore, it is desirable that the concentration of the additive in the oil range between 0.2 and 2% by weight and preferable that the additive be present in a concentration of about 0.5% by weight.

The utility and advantages of the invention will be demonstrated in ,the following example, it being understood, however, that the example is not to be considered as limitative in scope:

Example Comparative test runs were conducted with a standard Chevrolet passenger car engine made initially clean after each run by dismantling-removing the combustion chamber deposits and reassembling. In each run the engine was operated on a standard cycle procedure with an 11 spark advance to simulate city driving condi-.

tions. Each cycle included one minute at 500 R. P. M. with no load (idling conditions) and an air fuel ratio of 11.2, and 5 minutes at 2000 R. P. M., equivalent to 40 M. P. H. with 11.2 lbs. brake horsepower load, an air/fuel ratio of between 13.5 and 14.5, water outlet temperature of 160 F. and oil sump temperature of 190 F. This six minute cycle was repeated until the octane requirement of the engine had arrived at an equilibrium value. This required an average of about hours operation which is equivalent to approximately 4000 miles of city driving. Octane requirement measurements were made once each day under the following conditions:

Speed, R. P. M 1000 Load throttle fuel Jacket outlet F. Oil temperature F.

Spark advance 11 B. T. C. Air/fuel ratio 13.5

of combustion chamber deposits generally) and used oil properties are tabulated immediately below:

4 modifications are intended to be included within the scope ofthe' invention as 'defined in the accompanying claims.

Used Oil Properties Cone. Octane Piston Run Naphthenin Oil, Require- Top De- No. ate Addi- Percent merit posit Vis. C5 Insol- Benzene tive by wt. Increase Weight, Change, ubles, Insoluble,

grams SSU, at percent percent None 11 29.7 Ag 0. 5 7 26.,38 +171 3. 36 0.94 Cu' 0.5 7' 22:51 45 2. 48 0. 56 Ni 0.5 5 22.19 29.; 1.09 0. Ag+Cu 0 25/0. 25 5 9.19 -32 3. 76 0.1a Ag-i-Nr 0 25/0. 25 7 16:50 124 2.18 0.06

Hg 1 0.5 (i 29.99,; -41'; 2.30 0. 0; Hg+Cu 0 25/0. 25 9 27. 67 -51, 1.1L 0.38

Comparison of runs. Nos.: 1 and :2 shows that.wh1le I claim:

silver naphthenate alone --has za beneficial.r effect in suppressing octane requirement increase byfourv numbers, it.has 'very little eifect insinhibiting theformation of- '0 combustion chamber deposits-,anda somewhat deleterious. effect on the used oil properties inthat. the used oilshows a considerable increasein viscosity andhigh pen-. tane and benzene insolubles- Comparisons of runs. Nos. 3 and 4 with run No. 2 show that copper. and nickel naphthenates. alone have a comparableeffect in supressg ing octane requirementrincrease and are. slightly more; effective in.inhibiting theformation of combustionchamr berdeposits, the used oil, properties with copper.v and;

nickel. naphthenates alone being somewhat superior; to.

those found whenusilver naphthenate alone wasv eme, ployed. Run No. 5 demonstrates the. remarkablersyn crgistic effect obtainedby combining silver.:and.copper naphthenates :in that the piston-top .depositgweight,-is,

reduced from mean value of about,.24.5 for. silver and copper naphthenates alone to only 9.19 gramsand in sup pressing theoctane requirement increase to only. five numbers, whereassilver and copper. naphthenatesalone were efiective in suppressing the octane requirement-increase to; seven numbers. Thecombinatiomof silver and nickeL. naphthenates, as shown in the data for run No. .6, is also.

effective in inhibiting the formation of combustion chamber deposits (16.5 grams as-compared with a mean of approximately 24.3 grams for silver and nickel naphthenates alone).'but is not quite as efiective asthe' silver-,

prisingfa mixture-10fsilvernaphthenate with ametal copper naphthenate combination in suppressing octane.

requirement increase.

The used oil properties in runs;

Nos. 5 and 6, wherein-theadditive of the invention was employed, are also shown to be significantlybetterthan would be expected in view of the used. oil properties re sulting from the use of silver naphthenate alone.

Runs Nos. 7 and 8 are'includedto show'the, criticality of the combination of silver naphthenate with copper; or nickel naphthenate; Run No. 7 shows results obtained. by using mercury naphthenate alone andv run'No. 8 shows the results of using a combination of mercury andjcop per naphthenates. Where mercury naphthenate alone suppresses the octane requirement increase to six numbers and copper naphthenate alone to seven (run No. 3). it

weight,.the,.combinationofmercury .and. copper.- napthe-J. nates shows no synergistic. efiects...comparable to that.pro.-..

duced. by the combination. .ofisilver naphthenate-with either copper or nickelnaphthenate.-.

It is to be understoodthat various modifications will readily occur, to. those skilled in the art upon,r.eading,. It. is to be understood that all. such;

this description.

1. A'crankcase lubricating oil containing about 0.2 to about 2% by weight of an additive comprising a mixture of silver naphthenate with; anaphthenate selected from the group consisting of copper and nickel naphthemates.

2. A crankcase lubricating oil containing about 0.2 to about 2% by weight of an additive comprising a mixture of silver naphthenate with a naphthenate selected from the" group consisting of copper and nickel naphthemates; the silver naphthenate comprising from about 25 to about by weight'of-the additive.

3; Acrankcase, lubricating oil containing from; about 0.2"to about 2%"by weightof an additive comprisinga mixture of approximately equal parts by weight of-silvernaphthenate and" agmetal' naphthenate selected fronrthe group consisting oficopper and nickel; naphthenates;

4. Acrankcaselubricating oil'containing from about 0.2to' about. 2% by weight of an additive comprising a mixture of; approximately equal partsby weight of silverandjcopper"naphthenates.

5; A crankcase lubricating, oil' containing from; about 1 0.2"to about2%"',by weight of an additive comprisingamixture of approximately equal parts by'weight of silver and nickel naphthenates.

6;. An .additive'for a crankcase lubricating-oil comnaphthenate selected .from' the group'consisting of copper and nickel 'naphthenates.

7. An additive fora crankcase lubricating oil comprising aj mixture 'of *aboutj'25 to about 75 partsby weight of silver naphthenate-with about 25 to about 75' parts by weight of' a metal naphthenate selected from the group consisting of; copper, and nickel naphthenates.

8;? An additive 'for a crankcase lubricating oil compris ing .a mixture of approximatelyequal parts by weight of silver naphthenate and-of-a naphthenate selected fromthe group consisting of 'copper and nickel naphthenates.-

9:An,additive for acrankcase lubricating oil comprising a mixture' of approximately equal parts by weight ofsilver and coppernaphthenates.

10; An additive' for a crankcase lubricatingoil-com' prising a mixture of-approx-imately equal parts by weight of silver and nickel' naphthenates.

References'Cited in the file of this patent UNITED STATES PATENTS 2,343,756 Downing a Mar. 7, 1944 2,388.; 39 Raymond Nov. 6, 1945' 2,560,542 Bartleson July 17, 1951 THER REF RENCES- Jour; $00.; Chem.- Ind, (Japan), vol: 33"(1930). pages 318B and 319B; 

1. A CRANKCASE LUBRICATING OIL CONTAINING ABOUT 0.2 TO ABOUT 2% BY WEIGHT OF AN ADDITIVE COMPRISING A MIXTURE OF SILVER NAPHTHENATE WITH A NAPHTHENATE SELECTED FROM THE GROUP CONSISTING OF COPPER AND NICKEL NAPHTHENATES. 